1. Field of the Invention
The invention releates to bobbin winding mechanism for a sewing machine and more particularly to mechanism for replenishing thread on a bobbin while in place in a looptaker.
2. Description of the Prior Art
Mechanisms for replenishing thread on a bobbin while in place in a looptaker and while stitch forming instrumentalities remain operatively associated as required for sewing are well known. Such bobbin replenishing mechanisms may be seen for example in U.S. Pat. No. 3,115,855 of S. J. Ketterer for "Bobbin Thread Replenishing Means in Sewing Machine Loop Taker" issued Dec. 31, 1963, and in U.S. Pat. No. 3,693,566, also of S. J. Ketterer for "Bobbin Thread Replenishing Mechanism for Sewing Machines" issued Sept. 26, 1972.
A disadvantage of prior art bobbin thread replenishing mechanisms of the kind described has been their complexity and cost, due to the inclusion of camming devices for raising and lowering a drive shaft into and out of driving engagement with the bobbin. Further, the prior art mechanisms included threading devices which often proved difficult to thread.
It is a prime object of the present invention to provide an improved bobbin winding mechanism which can be simply and inexpensively constructed.
It is another object of the invention to provide an improved bobbin winding mechanism which is constructed to facilitate the threading of a tensioning device.
It is still another object to provide improved means for initialing and discontinuing the operation of bobbin winding mechanism.
Other objects and advantages of the invention will become apparent hereinafter.